EXPERIMENTS ON LIVING CINCHON2E. 
15 
loicl, but without at all diminishing the discrepancy. I am therefore compelled to believe 
either that the hypothesis is not true, or else that it is only true to a very partial extent ; 
in fact so partially as to render it of no assistance in the scientific culture of cin- 
chona. 
In order to test the hypothesis in another manner, the soil round some young trees of 
C. succirubra , which was naturally singularly poor in lime, was made, by constant dres- 
sing with well-exposed hydrate of lime, almost into a calcareous soil. After two years 
and a half the bark was analyzed and its ash determined. It yielded 6 - 23 per cent, of 
total alkaloids and 2 '91 per cent, of ash ; in other words, the presence of abundance of 
a powerful base in the soil had affected neither the amounts of alkaloids nor of ash. 
The crown barks offer a still further contradiction to the hypothesis. Trees growing 
close together may have nearly the same amount of ash and yet contain organic bases in 
nearly the proportion of 1 : 2. 
The results of Puttfarcken can be reconciled with mine. His analyses were per- 
formed with barks imported in the dry state from South America ; among these would 
be both trunk- and branch-bark. The increased amounts of ash and small amounts of 
alkaloid in the latter would at first present the appearance of substitution, and would 
mislead the investigator. I found the same, and was for some time misled also ; but 
a few experiments with the trank- and branch-barks of various other trees showed me 
that the latter contain more mineral bases than the former, just as in cinchona, although 
no alkaloids are present. At the latter end of the foregoing Table some instances of 
this are adduced. 
Furthermore, the fact that the greater part of the alkaloids exists in an insoluble state 
of combination in the cells of the bark, is itself somewhat adverse to the likelihood of 
the hypothesis being true ; since it is hardly likely that in this situation they can be 
very active constituents of the plant. 
